【摘要】 本文利用紫坪铺水库台网记录到的波形资料,计算了2004～2008年170个M_L≥1.0级地震的震源参数.紫坪铺水库震源参数计算结果与其他大陆地区有明显不同:(1)拐角频率远低于其他大陆地区结果,表明库区地震波传播经过了较强的衰减过程;(2)视应力计算结果比其他地区小3个数量级,可能是由于库区地震波的高频成分衰减强烈,低估了能量集中在高频的小地震的地震辐射能量.分析了蓄水前后拐角频率和地震矩以及视应力和地震矩关系(视应力标度率)变化,结果表明:相同地震矩的地震蓄水后拐角频率增加,地震高频成分相对丰富;蓄水前视应力与地震矩的关系不明显,蓄水后视应力随地震矩的增加而增加.视应力标度率的改变可能是蓄水后地震震源物理过程逐渐改变的直接反映.更多还原

【Abstract】 In this paper, 170 earthquake source parameters of M_L ≥1. 0 were calculated using waveform data observed from 2004 to 2008 by Zipingpu reservoir earthquake network. The result shows great difference to previous results calculated in some continental areas: (1) the corner frequencies are much lower than those in typical continental areas, it tells us that the seismic wave is subjected to great attenuation during propagation; (2) the value of apparent stress is less than other area by 3 orders of magnitude, it may be caused by the severe attenuation of high frequency components of source spectrum which leads to the underestimation of radiated energy. We also analyzed the difference of corner frequency versus seismic moment and apparent stress versus seismic moment before and after reservoir impounding. The corner frequencies of latter are bigger under the same seismic moment. There is no obvious correlation between apparent stress and seismic moment before reservoir impounding, but apparent stress increases with seismic moment after that. The difference of apparent stress scaling law may be a demonstration of transition of focal physical process.更多还原